This invention relates to a 3D viewing system, particularly to a stereoscopic LCD shutter glass driving method and apparatus.
Stereoscopic or three-dimensional vision may be created on a two-dimensional medium by creating a pair of stereoscopic images; a left eye image and right eye image. If a viewer sees only the left eye image with the left eye and the right eye image with the right eye, the viewer perceives a three dimensional image from the two stereoscopic images. Conventional video display devices produce an image by creating a plurality of horizontal display lines interlaced in two fields within a frame.
LCD shutter glasses are an electronically controlled set of glasses that are opened and closed under control of a video system. The switching of these shutters is commonly done at the field rate. That is, a left image LCD shutter lens is switched on during one field and the right LCD shutter lens is switched off during this field. The opposite is done in the other field. There is a need to keep these LCD shutter glasses as inexpensive as possible. In particular, it necessary to keep the control electronics of the LCD shutter glasses as inexpensive as possible. In addition, battery operation of such a device is necessary while still achieving the maximum performance from the LCD shutter glass shutters.
The embodiments of the invention include a method and apparatus for an economical method and apparatus for synchronizing the outputs of the left and right outputs of a 3D or stereoscopic video camera or other video output. A stereoscopic LCD Shutter glass driver for video signal input is a device that synchronizes the shutter of a pair of LCD shutter glasses with the fields of an NTSC, PAL, or other dual field video signal for the purpose of displaying a 3D stereoscopic image on a television set or other CRT based monitor system accepting these video signal formats. This driver has the effect of alternately blocking the view of the left (right) eye during display of field one and blocking the view of the right (left) eye during display of field two. If the input video signal has been properly formatted with left (right) perspective information on field one and right (left) perspective information on field two then the resulting image displayed on the television or CRT based monitor or other such device will appear to have stereoscopic depth when viewed through the LCD shutter glasses driven by the said driver system.
There are several existing 3D shutter glass driver systems for video including: StereoGraphics"" Simuleyes VR, and 3DTV Corp.""s StereoDriver(trademark) Model 2001. The invention described in this disclosure improves on these devices by greatly decreasing the number of components required to drive the shutter glasses and interpret the incoming video signal and thereby affecting a reduction in cost. In addition, power to the preferred embodiment of the invention described herein can be supplied by either a wall mounted 6-9 V DC power supply or by 4 AAA batteries. In addition to reduced cost, the reduced number of components lends itself to smaller size if so desired.
The stereoscopic LCD shutter glass driver system includes a sync separator coupled to a video input with a first output and a second output of said sync separator coupled to a first flip flop. In addition a third output of the sync separator is coupled to a negative charge pump. The negative charge pump provides a negative voltage to a second and third flip flop to generate pulses of greater amplitude than available with the power supply. A first output of the first flip flop is coupled to a second flip flop and a second output of the first flip flop coupled to a third flip flop. A first output of the second flip flop is coupled to a first terminal of a first (left or right image) LCD shutter glass, a second output of the second flip flop is coupled to a first terminal of a second (right or left) LCD shutter glass.
A first output of the third flip flop is coupled to a first input terminal of a switch and a second output of the third flip flop is coupled to a second input terminal of said switch. An output of the switch is coupled to a second terminal of the first LCD shutter glass and the second LCD shutter glass. This configuration produces a switching pulse train to each LCD shutter glass such that each LCD shutter glass is open every other field and the two shutter glasses are open and closed during opposite fields.